Engine mixing structures

ABSTRACT

A fuel and gas mixing structure for an engine is provided. This mixing structure includes a body configured to be positioned between a fuel injector and a cylinder of an engine. The body defines an interior volume that is configured to receive gas from outside the body and to receive one or more streams of fuel from the fuel injector in the interior volume. The body also defines one or more mixture conduits configured to conduct plumes of the fuel and gas, while mixing, from the interior volume to one or more exit ports and therethrough to the cylinder.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No.62/616,702, filed 12 Jan. 2018, and U.S. Provisional Application No.62/623,194, filed 29 Jan. 2018, the entire disclosures of which areincorporated herein by reference.

FIELD

The subject matter described herein relates to structures and assembliesthat reduce the formation of soot in engines.

BACKGROUND

In a compression ignition engine, fuel may be directly injected intocompressed hot gases, such as air or a mixture of air and recycledexhaust gas. The fuel mixes with these in-cylinder gases near the siteof injection of the fuel into the cylinders of the engine. As therelatively cool fuel mixes with the higher temperature gases, theresulting mixture reaches a temperature sufficient for ignition. Thismay be a dynamic event and fuel may be ignited and may burn at the headof a fuel spray plume while fuel continues to be injected into the otherend of the spray plume.

As the temperature of the gases entrained into the injected fuel remainshigh, the delay between injection of the fuel and ignition of thefuel-and-air mixture in a cylinder may be reduced. This may cause thefuel spray plume to have a sub-optimal fuel-and-air mix ratio beforeinitial ignition, which may produce soot. The production andconsequential build-up of soot may degrade performance of the engine andeventually require cleaning or other repair of the engine. Additionally,certain regulations or laws may restrict how much particulate matter orother emissions can be generated by engines.

BRIEF DESCRIPTION

In one embodiment, a mixing structure is provided that includes a bodydefining an axis and extending from an injector side toward an oppositepiston side along the axis. The body has an inward facing surfaceproximate to the axis that defines a central volume and an outwardfacing surface distal from the axis. The injector side of the body isconfigured to face a fuel injector of a cylinder of an engine while thepiston side of the body is configured to face a piston head of theengine cylinder. The body has one or more channel surfaces that defineone or more gas channels extending through the body to and from thecentral volume. The body also has one or more conduit surfaces thatdefine one or more fuel-and-gas mixture conduits extending through thebody to and from the central volume. The central volume is configured toreceive one or more streams of fuel from the fuel injector, and one ormore streams of gas from the one or more gas channels. During operation,at least one of the streams of the fuel mixes with the one or morestreams of gas to form a fuel-and-gas mixture at a designated ratio offuel to gas. The fuel-and-gas mixture conduits are configured to directthe fuel-and-gas mixture out of the body and into a combustion chamberof the engine cylinder.

In one embodiment, another mixing structure is provided. This mixingstructure includes a body configured to be positioned between a fuelinjector and a cylinder of an engine. The body defines an interiorvolume that is configured to receive gas from outside the body and toreceive one or more streams of fuel from the fuel injector in theinterior volume. The body also defines one or more mixture conduitsconfigured to conduct plumes of the fuel and gas, while mixing, from theinterior volume to one or more exit ports and therethrough to thecylinder.

In one embodiment, another mixing structure includes means forseparately receiving fuel from a fuel injector and receiving gas, meansfor mixing the fuel and the gas into a fuel-and-gas mixture at adesignated ratio, and means for directing the fuel-and-gas mixture intoa combustion chamber of an engine cylinder.

BRIEF DESCRIPTION OF THE DRAWINGS

The present inventive subject matter may be understood from reading thefollowing description of non-limiting embodiments, with reference to theattached drawings, wherein below:

FIG. 1 is a perspective view of one embodiment of a mixing structure fora cylinder of an engine;

FIG. 2 is partial cross-sectional view of the mixing structure shown inFIG. 1;

FIG. 3 illustrates a cross-sectional view of the mixing structure shownin FIGS. 1 and 2 coupled to a cylinder head of an engine cylinder in anengine according to one embodiment;

FIG. 4 illustrates another cross-sectional view of the mixing structureshown in FIGS. 1 and 2 coupled to the cylinder head of the cylindershown in FIG. 3 according to one embodiment;

FIG. 5 is a perspective view of another embodiment of a mixing structurefor a cylinder of an engine;

FIG. 6 is a perspective view of another embodiment of a mixing structurefor a cylinder of an engine;

FIG. 7 is a perspective view of another embodiment of a mixing structurefor a cylinder of an engine;

FIG. 8 is a perspective view of another embodiment of a mixing structurefor a cylinder of an engine;

FIG. 9 illustrates a side view of another embodiment of a mixingstructure;

FIG. 10 illustrates a perspective view of an injector side of the mixingstructure shown in FIG. 9;

FIG. 11 illustrates a cross-sectional view of the mixing structure alongline 11-11 shown in FIG. 9;

FIG. 12 illustrates another cross-sectional view of the mixing structurealong line 12-12 in FIG. 9;

FIG. 13 illustrates a side view of another embodiment of a mixingstructure;

FIG. 14 illustrates a perspective view of an injector side of the mixingstructure shown in FIG. 13;

FIG. 15 illustrates a side view of another embodiment of a mixingstructure;

FIG. 16 illustrates a perspective view of an injector side of the mixingstructure shown in FIG. 15;

FIG. 17 illustrates a side view of another embodiment of a mixingstructure;

FIG. 18 illustrates a perspective view of an injector side of the mixingstructure shown in FIG. 17;

FIG. 19 illustrates a side view of another embodiment of a mixingstructure;

FIG. 20 illustrates a perspective view of an injector side of the mixingstructure shown in FIG. 19;

FIG. 21 illustrates a side view of another embodiment of a mixingstructure;

FIG. 22 illustrates a perspective view of an injector side of the mixingstructure shown in FIG. 21;

FIG. 23 illustrates a perspective view of an alternative embodiment ofthe piston side of the mixing structure shown in FIGS. 9 through 12; and

FIG. 24 illustrates a perspective view of another embodiment of a mixingstructure.

DETAILED DESCRIPTION

One or more embodiments of the inventive subject matter described hereinprovide mixing structures or assemblies. The mixing structures orassemblies may be mechanical structures disposed at or near fuelinjectors of cylinders in an engine. The mixing structures may affectand/or control an ignition delay of the fuel (e.g., by delaying theignition relative to the time of injection). Ignition control may allowfor a different (e.g., leaner) fuel-and-air mixture to be achieved priorto the mixture arriving at a region of combustion to ignite or combust.Several concepts are described herein that facilitate this modificationof the fuel combustion event. Although tubes and ducts may be used insome assemblies, other mixing structures and assemblies define channels,flow paths, conduits, and the like and do not include a tube structurenor include a duct structure within the combustion chamber of acylinder. Some assemblies having tubes or ducts have been shown tosuffer from catastrophic failures, such as explosions occurring withinthe tubes.

With reference to some of such concepts, the mixing structures orassemblies may be placed in cylinder heads between the fuel injectorsand the pistons or may be disposed on top of the pistons. Suchassemblies may control (e.g., reduce) an amount of hot gas that isentrained into an injected fuel stream. A fuel injector may inject thefuel and may have a nozzle that forms a plurality of fuel streams.

By adding in these mixing structures, the fuel and air may have moretime to mix prior to igniting. The ratio of fuel to gas/air may becontrolled. The mixing process of the fuel and gas/air may becontrolled. It may be the case that controlling the mixing of fuel andgas/air may reduce or eliminate the production of certain exhaustproducts (e.g., soot, NOx) during the combustion process.

By adding in these mixing structures, the structure may contact the hotgas and air to act as a heat sink. In this way, it may locally cool thepreviously hot gas/air as it is incorporated into, entrained, and/orswept along with a fuel stream plume. The mixing structure may cool thegases that may be entrained into fuel streams injected into thecylinder. A cooler mixture may delay ignition and thereby reduce anamount of soot generated or prevent generation of soot altogether.Various embodiments of the mixing structure may be referred to as a sootreduction assembly or an engine assembly. As used herein, the terms gasor gases are inclusive of air, a combination of air and recycled exhaustgas (EGR), a combination of air and other diluents (e.g., water vapor,CO2, and/or N2, etc.), air modified to change the oxygen concentration,and a combination of any of the foregoing with aspirated natural gas.

FIG. 1 is a perspective view of one embodiment of a mixing structure 100configured for use in a cylinder of an engine. FIG. 2 is a partialcross-sectional view of the mixing structure shown in FIG. 1. The mixingstructure may be formed from a body 102 having one or more interior orcentral disposed volumes 124 that encircle a center axis ZC. The bodyextends along the center axis ZC from a fuel injector side 104 to anopposite piston side 106. The fuel injector side can face a fuelinjector when in an installed and operational condition so that itinjects fuel into the cylinder in coordination with the insert assembly.The piston side can face the crown or piston head of this same cylinder.

The mixing structure may attach or couple to the piston crown orcylinder head. The body may attach or couple to a cylinder head andremain stationary while a piston in the cylinder moves relative to themixing structure, the fuel injector, and the cylinder head. In oneembodiment, the body may be attached to the crown of the piston (e.g.,the end of the piston that may be closest to the fuel injector) and maymove toward and away from the fuel injector and cylinder head duringoperation of the piston.

In one embodiment, the body may include a step portion 108 and a secondportion 110 extending in directions along the center axis ZC. In theillustrated embodiment, the upper step has a smaller outer circumferencethan the outer circumference of the lower portion. The step may radiallyextend (relative to the center axis ZC) from an inner surface 112 to anopposite distal outer surface 114 and the second portion may define anannulus and radially extend (relative to the center axis ZC) from aninner surface 116 to an opposite distal outer surface 118. The outersurface of the second portion may be located farther from the centeraxis ZC than the outer surface of the upper step. In other embodiments,the upper step and/or second portion has an outer surface that may belocated a different distance from the center axis ZC; or, the innersurface of the second portion may be located farther from the centeraxis ZC than the inner surface of the upper step. The transition betweenthe step portion and the second portion may be smooth or may have atexture or surface profile; and, it may be at about a 90-degree anglerelative to at least one of the step portion or the second portion, ormay have a linear profile and be angle at about 45 degrees towards oraway from the outer periphery; and, the transition may have a nonlinearprofile and bow or undulate in a convex or concave manner. In oneembodiment, at least one segment of the surface of the step portion maybe configured to direct exhaust gas from inside the cylinder to aproximate exhaust valve. In one embodiment, at least one other segmentof the surface of the step portion may be configured to affect orcontrol a flow of intake gas (or intake gas and natural gas for amulti-fuel capable engine) into the cylinder. The configuration ofthese, and other aspects of the topology, have varying levels of impacton a host of performance factors. As such, the selection and combinationof configuration factors may be selected with reference to the enginetype, fuel type, cylinder/piston size, duty cycle of the engine,regulation for emissions, fuel consumption rates, EGR levels, the use ofmulti-fuel systems, and the like. While some specific combinations offeatures are set forth herein for examples, other combinations may beused in conjunction with features external to the inventive device toachieve desired outcomes in specific applications.

The step portion and second portion may be connected by one or more gaschannels 101. In the illustrated embodiment, the gas channels may beintegrally formed from, or defined by, surfaces of one or more coolingfins 120. The fins may be spaced apart from each other incircumferential directions that encircle the center axis ZC. The finsradially extend from the inner surface of the upper step to the outersurface of the upper step. In the illustrated embodiment, the fins eachhave an undulating or wavy shape or configuration. This shape mayincrease the surface area of the fins (e.g., relative to flat ornon-undulating fins) and create more interaction between hot gases andthe surfaces of the fins for more thermal transfer of the gases, asdescribed herein.

In another embodiment, other fins may have a different shape, size orthickness. For example, some other fins may have a generally flat shapewith a smooth finish. A smooth finish may help reduce pressure dropacross the length of the fin. In other embodiments, the fin surface maydefine a plurality of protuberances that extend away from the surfacesof the fins into the gas channels, and/or may define dimples or groovesthat inwardly extend into the surfaces of the fins away from the gaschannels. The shape of the fins; the number, spacing, arrangement sizeand profile of the protuberances and/or dimples and/or grooves; and theangle, finish and surface characteristics of each fin may affect thebehavior and flow paths of gas received into the center volume of themixing structure through the gas channels from outside of the mixingstructure.

The second portion of the body may include several fuel-and-gas mixtureconduits 122. These mixture conduits extend from the inner surface ofthe second portion to the outer surface of the second portion. Themixture conduits may be oriented at transverse angles with respect tothe center axis ZC. For example, the center axes of the mixture conduitsmay be oriented at an acute angle that may be more than zero degrees andless than ninety degrees relative to the center axis ZC, with themixture conduits angled away from the upper step. In one embodiment, thecenter axes of other mixture conduits may be oriented at another angle,such as a ninety degree or obtuse angle relative to the center axis ZC.There are several mixture conduits shown in FIGS. 1 and 2 (although onlytwo are be labeled). The mixture conduits may be symmetricallydistributed or arranged around the center axis ZC. In other embodiments,a different number of the mixture conduits is provided, for example asingle mixture conduit may be used. The mixture conduits shown have acylindrical shape, but alternative suitable shapes may include a fanshape, a conical shape, a polygon shape, a square cross-sectional shape,a rectangular cross-sectional shape, another polygon cross-sectionalshape, an oval cross-sectional shape, and the like.

In any of the embodiments herein, the gas channels and/or thefuel-and-gas mixture conduits may be radially symmetrically distributedaround and relative to the center axis ZC, such that there is an evenamount of radial spacing between each adjacent pair of channels orconduits (that is, the radial spacing between one channel or conduit andits nearest two neighboring channels or conduits on either side is thesame as the radial spacing between all other channels or conduits andtheir respective nearest two neighboring channels or conduits on eitherside). Further, in any of the embodiments, a total number of thechannels may be same as, or different from, a total number of aconduits. Also, the radial spacing between adjacent channels may be thesame as, or different from, the radial spacing between adjacentconduits. In one embodiment, there is a larger total number of gaschannels than fuel-and-gas mixture conduits, and the gas channels arespaced radially closer to one another than the fuel-and-gas mixtureconduits.

In one embodiment, the body may include the step portion and thereby toincrease the distance between the mixture conduits and the fuelinjector, while avoiding contact between the body and one or more valvesof the fuel injector. Without the step portion the circumferential sizeof the body nearest the fuel injector would be much larger. This mightcause the insert to contact or interfere with operation of the valves ofthe cylinder head.

In one embodiment, the mixing structure may be created using additivemanufacturing. For example, at least the fins of the cooling assemblymay be formed using a three-dimensional printing system. In oneembodiment, the mixing structure may be cut from a larger body ormachined in another way. Suitable materials for the mixing structure maybe a thermally conductive material. In one embodiment, the mixingstructure may be formed from a metal or metal alloy. In differentembodiments, the mixing structure may be a ceramic or a cermet (e.g., amixture of one or more ceramics and one or more metals), or a ceramicmatric composite. The mixing structure may not be a homogeneousmaterial. In one embodiment, the surface material differs from theinternal material. This can be done during the manufacture process ormay be done by coating or treating the surface of the mixing structure.Coatings may include wear resistant materials (such as diamond-likecoatings, DLC) or may be active (such as catalysts) to affect thecombustion event itself.

FIG. 3 illustrates a cross-sectional view of the mixing structure shownin FIGS. 1 and 2 coupled to a cylinder head 300 of an engine cylinder302 in an engine according to one embodiment of the inventive subjectmatter. FIG. 4 illustrates another cross-sectional view of the mixingstructure shown in FIGS. 1 and 2 coupled to the cylinder head of thecylinder shown in FIG. 3 according to one embodiment of the inventivesubject matter.

The mixing structure may be affixed to the cylinder head in a locationbetween a fuel injector 304 and a crown 306 of a piston 308 in thecylinder. The piston moves toward and away from the fuel injector duringoperation of the engine, or up and down in the perspective of FIGS. 3and 4. In the illustrated embodiment, the mixing structure may bestationary as the mixing structure may be mounted or otherwise affixedto the cylinder head. The piston moves toward and away from both thefuel injector and the stationary mixing structure. In one embodiment,the mixing structure, or cooling assembly, may be affixed or otherwisecoupled to, or incorporated into the crown of the piston such that themixing structure moves with the piston toward and away from the fuelinjector.

In operation, the fuel injector injects one or more streams of fuel 400into the central volume of the mixing structure body. During operation,the fuel streams flow from the fuel injector through the central volume(shown in FIG. 1) of the mixing structure. The pressure supplied to thefuel injector may cause all or substantially all (e.g., at least 90%) ofthe fuel to pass through the mixture conduits (after mixing with gases,as described herein).

As the fuel flows into the internal volume of the body, the moving fueldraws gases 402 through the mixing structure. The gases, which may berelatively hot, may be pulled through the gas channels between the finssuch that the hot gases move inward from outside the mixing structure,through (e.g., between) the fins, and into the center volume of themixing structure. The fins allow the hot gases to pass from outside thebody of the mixing structure to inside the step portion and secondportion (e.g., along radial directions toward the center axis ZC). Inone embodiment, all or substantially all the gases drawn into theinterval volume of the body pass through the gas channels between thefins, with no or little to no (e.g., no more than 10%) gases being drawninto the center volume through the piston side or injector side of themixing structure.

Each fin may operate as a heat sink to transfer thermal energy. In oneembodiment, the thermal energy may transfer out of the hot gases. The atleast partially cooled gases then become entrained in the flow of fuelin the center volume to form a fuel-and-gas mixture 401 inside thecenter volume of the body. This fuel-and-gas mixture may be formedbefore the fuel or gas enters the combustion chamber of the cylinder.The fuel and gas mixes to form the fuel-and-gas mixture, which flows outof the mixing structure via one or more of the mixture conduits. Thefuel-and-gas mixture then flows into the combustion chamber of thecylinder. This fuel-and-gas mixture may be cooler than fuel-and-gasmixtures that do not flow through or mix within the mixing structure,which may delay ignition inside the chamber of the cylinder and preventor reduce soot formation, as described herein.

Optionally, the mixture conduits may be oriented to direct thefuel-and-gas mixture farther into the combustion chamber of the cylindersuch that the fuel-and-gas mixture penetrates further into thecombustion chamber (e.g., compared to directing the fuel and gas intothe combustion chamber without mixing the fuel and gas using the mixingstructure. For example, mixing the fuel and gas in the body and thendirecting the fuel-and-gas mixture into the combustion chamber using theconduits may change the combination of mass and velocity of the mixturejet relative to the mass and velocity that the fuel and gas jet wouldseparately have without pre-mixing the fuel and gas in the mixingstructure. For example, the jet with the mixing structure may be moreconfined (e.g., narrower) than the jet would be without the mixingstructure. Additionally, the jet may have lower initial mass entrainmentbut higher velocity relative to the jet without the mixing structure.Without mixing structure, the jet could entrain more gases earlier inthe flow path, which would have a high mass within the domain of thespray and spreading the spray resulting in a lower velocity and lowerpenetration into the cylinder. The more concentrated, higher velocity ofthe mixture by the structure causes the mixture to enter farther intothe combustion chamber to locations that may be farther from thestructure (relative to not using the structure). As the penetration ofthe mixture into the combustion chamber increases, soot oxidation withinthe combustion chamber may be enhanced, which may eliminate or reducethe amount of soot in the engine cylinder.

The conduits may be shown as passageways having continuous walls thatmay be only open at the opposite ends of the conduits. In oneembodiment, one or more (or all) of the conduits may includeperforations, holes or slits distributed along the length of theconduits. These perforations or holes may be radially distributed alongthe lengths of the conduits, such that the perforations or holes may beat different radial distances from the axis ZC. The holes orperforations may allow additional gas to be drawn into the conduits,mixed with the fuel, and cooled before being directed into the cylinder.The arrangement, placing, size, and angle of the holes or perforationsmay affect the fuel-to-gas ratio of the mixture via the gas volumeadded, and the level of homogeneity of the mixture via the mixing effectcaused by the impact of the inflowing gas streams, and the orientationof the mixture relative to the conduit inner walls by creating a bufferlayer along the wall (i.e., the mixture stream can be concentricallymoved through the conduit without contacting the sides). A laminar flowof gases may flow alongside the mixture stream and urge the mixturestream towards the center of the conduit.

In one embodiment, the mixture conduits may be defined by one or moreexposed inner surfaces extending through the body. These inner surfacesmay be cylindrical surfaces in FIGS. 1 and 2, but in other embodimentsmay have another shape. The shape may be selected based, at least inpart, on application specific parameters. For example, these surfacesmay have a conical shape such that the sizes of the openings of theconduits on the outer surface may be larger than the sizes of theopenings of the conduits on the inner surface. As another suitableconfiguration example, the surfaces may have a conical shape with thesizes of the openings of the conduits on the outer surface being smallerthan the sizes of the openings of the conduits on the inner surface. Invarious embodiments, the surfaces may be smooth surfaces or may haveprotuberances or dimples. The protuberances or dimples may change theflow paths of fuel-and-gas mixtures through the conduits to controlfeatures of the flow, such as how far the fuel-and-gas mixturespenetrate the combustion chamber of the engine cylinder or the degree ofturbulence and/or mixing. This may change the degree to which there isturbulent flow rather than laminar or plug flow of the mixture.Optionally, the dimples or protuberances can facilitate mixing of thegases and fuel by causing a more turbulent flow of the gases and/or fuelthat increases the degree to which the gases and fuel are more evenlymixed in the mixtures.

Suitable conduits also may have linear cylindrical shapes. For example,each conduit may be centered around or along a linear axis. In oneembodiment, one or more of the conduits may have a curved shape. Forexample, the conduits may have curved shapes such that the conduits maybe centered around curved axes having the same or different radii ofcurvature.

The shape of the conduits, size of the conduits, linear or curved pathsof the conduits, presence of protuberances and/or dimples in theconduits, and/or perforations or holes extending to the conduits mayimpact the momentum and/or direction and/or angular momentum in whichthe fuel-and-gas mixture exits from the mixing structure. One or more ofthese parameters may be varied or change for mixing structures used fordifferent types of fuels, for different temperatures of gas, fordifferent engines, for different cylinders, or the like, to control howfar the fuel-and-gas mixture penetrates the combustion chambers of theengine cylinders.

FIG. 5 is a perspective view of another embodiment of a mixing structure500 for a cylinder of an engine. The mixing structure optionally may bereferred to as a soot reduction assembly because the mixing structurecools the gases that may be entrained into fuel injected into thecylinder, thereby delaying ignition and reducing the amount of sootgenerated or preventing generation of soot. Additionally, the mixingstructure may direct the fuel-and-gas mixture farther into thecombustion chamber of an engine cylinder. This may oxidize more soot.

The mixing structure shown in FIG. 5 has some features similar oridentical to the mixing structure shown in FIGS. 1 and 2. The mixingstructure may be formed from a body 502 having a shape that extendsaround a center axis ZC in the center or central volume. While variousmixing structures may be shown as having a single center volume, in oneembodiment, the mixing structures may include one or more interior wallsthat divide the central volumes into two or more smaller centralvolumes.

The body extends along the center axis ZC from the fuel injector side104 to the opposite piston side described above. The body of the mixingstructure may be attached to a cylinder head or may be attached to thecrown of the piston and may move toward and away from the fuel injectorand cylinder head during operation of the piston.

The body may include the upper step and the second portion. In contrastto the mixing structure, the body of the mixing structure does notinclude any fins between the step portion and portion or any airpassages radially extending through the step portion. Instead, the upperstep portion and second portion may be connected by a solid wall 526. Asdescribed above, the second portion may include one or more mixtureconduits.

During operation, the fuel injector injects the fuel into the centralvolume of the mixing structure. The moving fuel draws the hot gasesthrough the mixing structure. The hot gases may be pulled into thecenter volume and mix with the fuel inside the center volume to form thefuel-and-gas mixture. This mixture may be directed out of the mixingstructure and into the combustion chamber of the cylinder through themixture conduits. The body of the mixing structure may operate as a heatsink to draw thermal energy out of the hot gases and cool the gasesbefore, during, and/or after the gases mix with the fuel inside thecenter volume. The at-least-partially-cooled gases then become entrainedin the flow of fuel in the center volume, and flow as the fuel-and-gasmixture out of the mixing structure via one or more of the conduits. Thefuel-and-gas mixture then flows into the combustion chamber of thecylinder. This fuel-and-gas mixture may be cooler than fuel-and-gasmixtures that do not flow through or mix within the mixing structure,which may delay ignition inside the chamber of the cylinder. Delayedignition may prevent or reduce soot formation, as described herein.

FIG. 6 is a perspective view of another embodiment of a mixing structure600 for a cylinder of an engine. As noted herein, embodiments of themixing structure optionally may be referred to as a soot reductionassembly. In such embodiments the mixing structure may cool the gasesthat may be entrained into fuel injected into the cylinder, therebydelaying ignition and reducing the amount of soot generated orpreventing generation of soot. Additionally, the mixing structure maydirect the fuel-and-gas mixture farther into the combustion chamber ofan engine cylinder to oxidize more soot.

The mixing structure may be formed from a body 602 having a shape thatextends around a center axis ZC in one or more central volumes (notvisible in FIG. 6, but shaped identical or similar to the centralvolume). The body extends along the center axis ZC from a fuel injectorside 604 to an opposite piston side 606. The fuel injector side faces afuel injector that injects fuel into the cylinder with which the mixingstructure may be associated. The piston side faces the crown of thepiston in this same cylinder.

The body may be a single piece body, such as a body that may be printedas a single, continuous body. For example, the body may be a monolithicbody formed from a single body of material and not formed from two ormore pieces that are joined together. The single piece body may not haveany seams or interfaces that would exist if the body were formed by twoor more pieces joined together, with the seams or interfaces present atthe locations where the pieces are joined together. Alternatively, thebody may be formed from two or more separate pieces.

The body of the mixing structure may be attached to a cylinder head(with the fuel injector also attached to the cylinder head) and remainstationary while a piston in the cylinder moves relative to the mixingstructure, the fuel injector, and the cylinder head. In one embodiment,the body may be attached to the crown of the piston (e.g., the end ofthe piston that may be closest to the fuel injector) and may move towardand away from the fuel injector and cylinder head during operation ofthe piston. In an alternative embodiment, the body may be formed fromtwo or more separate (e.g., not coupled) parts, with one part beingcoupled with the top of the piston and another part coupled with thecylinder head.

The body may include an upper portion 608 (having the step) and a secondportion 610 spaced apart from each other along the center axis ZC. Theupper portion may include a cylindrical stage or portion 628 (e.g., thestep) and a conical stage or portion 630. The cylindrical stage has anouter surface 614 that may be at or approximately at (e.g., withinmanufacturing or printing tolerances) the same radial distance away fromthe center axis ZC. The conical stage has a cone shape that extendsfarther away from the center axis ZC in locations that may be fartherfrom the cylindrical stage. The conical stage flares out or away fromthe center axis ZC. For example, the outer surface of the body at theend of the conical stage that intersects the cylindrical stage may becloser to the center axis ZC than the opposite end of the conical stage.

The second portion also has a conical shape that flares away from thecenter axis ZC. The conical stage of the upper portion and the conicalportion form concentric cones or portions of cones that may be centeredon or along the center axis ZC. The portions may be connected by one ormore spacers 620. In the illustrated embodiment, the spacers may becolumns that extend from a bottom surface 638 of the conical stage ofthe upper portion to an opposing upper surface 640 of the conicalportion.

The cylindrical stage of the upper portion may include several of thefins that may be spaced apart from each other in circumferentialdirections that encircle the center axis ZC to form the gas passages orchannels. The fins radially extend from the inner surface of thecylindrical stage of the upper portion to the opposite outer surface ofthe cylindrical stage of the upper portion.

In operation, the fuel injector injects the fuel into the internalvolume of the mixing structure. The moving fuel draws the hot gasesthrough gas channels and into the mixing structure. All or substantiallyall gases drawn into the central volume may be pulled through the gaschannels in one embodiment. The hot gases may be pulled into the centervolume through the gas channels between the fins by the flow of fuel.

The fins operate as heat sinks to draw thermal energy out of the hotgases and cool the gases, similar to as described above in connectionwith the embodiment of the mixing structure shown in FIGS. 1 through 4.The at least partially cooled gases then become entrained in the flow offuel in the center opening to form the fuel-and-gas mixture inside thecentral volume of the mixing structure. This mixture then flows out ofthe mixing structure via a space 601 between the bottom surface of theconical stage of the upper portion and the upper surface of the conicalportion. In one embodiment, some of the mixture may flow out of a centeraperture 603 (shown in FIG. 8) that may be fluidly coupled with thecentral volume and around which the conical portions encircle.Alternatively, some of the gas flowing into the center aperture that isentrained with the fuel to form the fuel-and-gas mixture can enter thecenter aperture from outside of the mixing structure through the centeraperture.

The fuel-and-gas mixture then flows into the combustion chamber of thecylinder. This fuel-and-gas mixture may be cooler than fuel-and-gasmixtures that do not flow through or mix within the mixing structure,which may delay ignition inside the chamber of the cylinder and preventor reduce soot formation, as described herein.

In one embodiment, the mixing structure may have an outlet through whichthe fuel-and-gas mixture leaves the body of the mixing structure, whichmay be a continuous or nearly continuous circle. By way of contrast,some other of embodiments have the fuel-and-gas mixture exit the mixingstructures through separate and spaced apart conduits and, as a result,several plumes of the fuel-and-gas mixture come out of the mixingstructures at discrete locations along the outer perimeter orcircumference of the second portion of the structures. The concentriccones in the body of the mixing structure direct the fuel-and-gasmixture to leave the body along all or substantially all (e.g., at least90%) of the outer perimeter or circumference of the conical portion. Thespacers 620 may disrupt or partially block the flow of the fuel-and-gasmixture out from the body in corresponding locations. But, thefuel-and-gas mixture may flow over the remainder of the outer perimeteror circumference of the conical portion. This may spread thefuel-and-gas mixture over a larger volume prior to entering thecombustion chamber of the engine cylinder, which may further cool thefuel-and-gas mixture for the reduction or elimination of sootgeneration.

In one embodiment, the upper portion and the lower (e.g., conical)portion may be separate bodies. For example, the spacers, columns, orconnectors may be fixed with one of the upper portion or the conicalportion, but not both. Instead, the spacers may be fixed to the upperportion or the conical portion, but not the other of the conical portionor the upper portion. The upper portion may be coupled with the cylinderhead, while the conical portion may be coupled with the crown of thepiston. The portions 608, 610 may be brought into contact, or closeproximity, with each other when the piston moves toward the fuelinjector (and the fuel injector injects fuel into the mixing structure).The portions 608, 606 may be separated from each other when the pistonmoves away from the fuel injector.

FIG. 7 is a perspective view of another embodiment of a mixing structure700 for a cylinder of an engine. This mixing structure may be referredto as a soot reduction assembly because the mixing structure cools thegases that may be entrained into fuel injected into the cylinder,thereby delaying ignition and reducing the amount of soot generated orpreventing generation of soot. Additionally, the mixing structure maydirect the fuel-and-gas mixture farther into the combustion chamber ofan engine cylinder to oxidize more soot.

The mixing structure may be formed from a body 702 having a shape thatextends around a center axis ZC in the central volume. The body extendsalong the center axis ZC from the fuel injector side to the oppositepiston side described above in connection with the mixing structure. Thefuel injector side faces a fuel injector that injects fuel into thecylinder with which the mixing structure may be associated. The pistonside faces the crown of the piston in this same cylinder.

The body of the mixing structure may be attached to a cylinder head(with the fuel injector also attached to the cylinder head) and remainstationary while a piston in the cylinder moves relative to the mixingstructure, the fuel injector, and the cylinder head. In one embodiment,the body may be attached to the crown of the piston (e.g., the end ofthe piston that may be closest to the fuel injector) and may move towardand away from the fuel injector and cylinder head during operation ofthe piston.

The body may include an upper portion 708 that may be based on acombination of the upper step of the mixing structure shown in FIG. 5and the upper portion of the mixing structure shown in FIG. 6. The upperportion may include a solid ring portion or stage 728 (e.g., similar tothe upper part of the upper step of the mixing structure that mayinclude the solid wall 526) and a conical stage.

The body may include several of the components described herein inconnection with other embodiments. For example, the body may include asolid wall (instead of the air channels and fins) that is describedabove in connection with the mixing structure shown in FIG. 5, theconical stage that may be coupled with the wall (and that forms part ofthe upper portion with the wall), and the lower conical portion.

One difference between the body of the mixing structure and the body ofthe mixing structure shown in FIG. 6 may be the number and arrangementof spacers in the body. The body may include several thin columns thatform the spacers. The spacers may differ in number, size, thickness,length, profile and material from embodiment to embodiment. An increasednumber and thinner shape of the spacers may assist with mixing thefuel-and-gas mixture as this mixture flows in the space between theconical stage and the conical portion, and also may increase the surfacearea that contacts the fuel-and-gas mixture. That is, the spacers mayoperate as heat sinks and may dissipate thermal energy from thefuel-and-gas mixture in a manner similar to the fins described herein.

In operation, the fuel injector injects the fuel into the central volumeof the mixing structure. The moving fuel draws the hot gases through themixing structure. The hot gases may be pulled into the central volumebetween the fuel injector side of the body and the fuel injector,similar to how the hot gases may be drawn into the body of the mixingstructure.

The gases then become entrained in the flow of fuel in the centralvolume, and flow as the fuel-and-gas mixture out of the mixing structurevia the space between the conical stage 630 of the upper portion and theconical portion. The fuel-and-gas mixture may flow between the spacers,and the spacers may operate as heat sinks to cool the fuel-and-gasmixture. The fuel-and-gas mixture then flows into the combustion chamberof the cylinder. This fuel-and-gas mixture may be cooler thanfuel-and-gas mixtures that do not flow through or mix within the mixingstructure, which may delay ignition inside the chamber of the cylinderand prevent or reduce soot formation, as described herein.

Similar to the mixing structure, the outlet through which thefuel-and-gas mixture leaves the body of the mixing structure may be acontinuous or substantially continuous circle. The concentric cones inthe body of the mixing structure direct the fuel-and-gas mixture toleave the body along all or substantially all (e.g., at least 90%) ofthe outer perimeter or circumference of the conical stage 630. Thespacers may disrupt or partially block the flow of the fuel-and-gasmixture out from the body in corresponding locations. But, thefuel-and-gas mixture may flow over the remainder of the outer perimeteror circumference of the conical portion. This may spread thefuel-and-gas mixture over a larger volume, which may further cool thefuel-and-gas mixture for the reduction or elimination of sootgeneration.

FIG. 8 is a perspective view of another embodiment of a mixing structure800 for a cylinder of an engine. The mixing structure optionally may bereferred to as a soot reduction assembly because the mixing structurecools the gases that may be entrained into fuel injected into thecylinder, thereby delaying ignition and reducing the amount of sootgenerated or preventing generation of soot. Additionally, the mixingstructure may direct the fuel-and-air mixture farther into thecombustion chamber of an engine cylinder to oxidize more soot.

The mixing structure may be formed from a body 802 having a shape thatextends around a center axis ZC in the central volume. This body extendsalong the center axis ZC from the fuel injector side to the oppositepiston side described above in connection with other cooling assemblies.The fuel injector side faces a fuel injector that injects fuel into thecylinder with which the mixing structure may be associated. The cylinderside faces the crown of the piston in this same cylinder.

The body of the mixing structure may be attached to a cylinder head(with the fuel injector also attached to the cylinder head) and remainstationary while a piston in the cylinder moves relative to the mixingstructure, the fuel injector, and the cylinder head. In one embodiment,the body may be attached to the crown of the piston (e.g., the end ofthe piston that may be closest to the fuel injector) and may move towardand away from the fuel injector and cylinder head during operation ofthe piston.

The body may include several of the components described herein inconnection with other embodiments. The body may include the upperportion that may be based on a combination of the upper step of themixing structure shown in FIG. 5 and the upper portion of the mixingstructure shown in FIG. 6, and that may be described above in connectionwith the mixing structure shown in FIG. 7. The upper portion may includethe solid ring portion or stage and the conical stage. The body mayinclude a solid wall described above, the conical stage that may becoupled with a wall, and the lower conical portion. The body also mayinclude one or more spacers that connect the conical stage and theconical portion.

In operation, the fuel injector injects the fuel into the central volumeof the body. The moving fuel draws the hot gases through the mixingstructure. The hot gases may be pulled into the center opening betweenthe fuel injector side and the fuel injector.

The gases become entrained in the flow of fuel in the central volume,and flow as the fuel-and-gas mixture out of the mixing structure via thespace between the conical stage of the upper portion and the conicalportion. Some of the mixture may exit the structure via the aperture.The fuel-and-gas mixture may contact the body within this space andtransfer thermal energy to the body to cool the fuel-and-gas mixture.The fuel-and-gas mixture then flows into the combustion chamber of thecylinder. This fuel-and-gas mixture may be cooler than fuel-and-gasmixtures that do not flow through or mix within the mixing structure,which may delay ignition inside the chamber of the cylinder and preventor reduce soot formation, as described herein.

Additionally, the outlet through which the fuel-and-gas mixture leavesthe body of the mixing structure may be a continuous or substantiallycontinuous circle, as described above. The fuel-and-gas mixture may bespread out over a larger volume, which may further cool the fuel-and-gasmixture for the reduction or elimination of soot generation.

The cooling assemblies described herein may be a single piece body withall parts and components secured with each other and with a common othercomponent (e.g., the entire body of the mixing structure may be fixed tothe cylinder head or the piston, but not both). In one embodiment, oneor more of the cooling assemblies may be formed from a multi-piece body,with one part of the body (e.g., the upper portion or step) beingcoupled with the cylinder head and another part of the body (e.g., thelower portion) being coupled with the crown of the piston. These partsmay be brought into contact or close proximity with each other as thepiston moves toward the fuel injector (and fuel may be injected into thebody by the fuel injector) and may move apart as the piston moves awayfrom the fuel injector.

In one embodiment, a mixing structure for a cylinder in an engine may beprovided. The mixing structure may include an annular body encircling acenter opening and a center axis. The annular body may be shaped to beplaced between a fuel injector of the cylinder and a piston in acombustion chamber of the cylinder. The annular body may be shaped toreceive fuel from the fuel injector into the center opening of theannular body along the center axis. The annular body also may be shapedto draw hot gas into the center opening to become entrained with thefuel flowing in the center opening from the fuel injector. The annularbody may be shaped to direct a mixture of the hot gas and the fuel thatmay be injected across the annular body to reduce a temperature of themixture of the hot gas and the fuel prior to directing the mixture ofthe hot gas and the fuel into the combustion chamber of the cylinder.

Optionally, the annular body may include an upper annulus and a lowerannulus coupled with each other; the upper annulus has an outercircumference that may be closer to the center axis than an outercircumference of the lower annulus; the lower annulus flares outwardaway from the upper annulus and the center axis; the upper annulus maybe located closer to the fuel injector than the lower annulus while theannular body may be placed between the fuel injector of the cylinder andthe piston in the combustion chamber of the cylinder; the upper annulusmay include several fins oriented along radial directions toward thecenter axis and spaced apart from each other in directions that may beparallel to an outer circumference of the upper annulus; the fins may bepositioned in the upper annulus such that the hot gas may be drawn intothe center opening between the fins by the flow of the fuel in thecenter opening. The fins may cool the hot gas as the hot gas flowsbetween the fins; the upper annulus of the annular body may include aconical stage that flares away from the center axis; the lower annulusof the annular body has a conical shape that flares away from the centeraxis; the upper annulus of the annular body may include a conical stagethat flares away from the center axis. The lower annulus of the annularbody may have a conical shape that flares away from the center axis; theconical stage of the upper annulus and the lower annulus may be spacedapart from each other in directions that may be parallel to the centeraxis; the annular body may be shaped such that the mixture of the hotgas and the fuel flows out of the annular body through a volume betweenthe conical stage of the upper annulus and the lower annulus; theassembly also may include spacer columns that may be coupled to andconnect the conical stage of the upper annulus and the lower annulus;the annular body may include several conduits that fluidly couple thecenter opening with locations outside of the annular body; the conduitsmay be elongated in directions that may be transverse to the centeraxis; the conduits may be elongated in directions that direct themixture of the hot gas and fuel away from the center axis; the annularbody extends in directions parallel to the center axis from a fuelinjector side that may be positioned to face the fuel injector to anopposite cylinder side that may be positioned to face the piston in thecombustion chamber of the cylinder; the annular body may be shaped todraw the hot gas into the center opening between the fuel injector sideof the body and the fuel injector; the annular body may be configured tobe coupled with a cylinder head of the cylinder; the annular body may beconfigured to be coupled to a top side of the piston; the annular bodyhas an opening that faces the fuel injector and into which the fuel maybe injected from the fuel injector into the annular body; the annularbody may be formed from a first annulus and a second annulus. The firstannulus may be configured to be coupled with a cylinder head of thecylinder that also may be coupled with or may include the fuel injector.The second annulus may be coupled with the piston.

FIG. 9 illustrates a side view of another embodiment of a mixingstructure 900. FIG. 10 illustrates a perspective view of an injectorside 908 of the mixing structure shown in FIG. 9. FIG. 11 illustrates across-sectional view of the mixing structure along line 11-11 shown inFIG. 10. FIG. 12 illustrates another cross-sectional view of the mixingstructure along line 12-12 in FIG. 9. The mixing structures describedherein optionally may be referred to as engine assemblies.

The mixing structure may include a body 904 that defines an axis 906 andthat extends from an injector side 908 toward an opposite piston side910 along the axis. The body may include a cylinder head interfacestructure or portion 926 and a thermal management structure 914. Thecylinder head interface structure couples with a cylinder head, whilethe thermal management structure faces a crown of a piston. Theinterface structure of the body is shrink fit into place. For example,the body may be formed from one or more materials that shrink in sizeafter installation and/or use. The body can be formed to have dimensionsthat, after the body shrinks, the dimensions match or fit thecomponent(s) to which the body is to be joined. In other embodiments,structures may be press fit, welded, bolted to, threaded onto (e.g.,screwed onto), or formed as part of a cylinder head of an enginecylinder in various other embodiments.

In one embodiment, the axis may be a center axis that the bodysymmetrically extends around or encircles. In one embodiment, the axismay not extend along the center of the body and/or the body may not besymmetric around or about the axis. The injector side of the body facesa fuel injector of an engine cylinder while the piston side of the bodyfaces a piston head of the engine cylinder.

The body has an opposite inward facing surface 1000 proximate to theaxis. This inward facing surface defines one or more central volumes1002 inside the body. While only a single central volume 1002 may beshown in FIGS. 10 and 11, in one embodiment, the body may include one ormore internal walls or other structures that divide the single centralvolume into two or more smaller volumes. The volume may be referred toas an injection chamber. The injection chamber may have a shape thatdecreases in cross-sectional size in locations that may be farther fromthe injector side of the body. For example, the injection chamber may bestaged in diameter such that different locations of the injectionchamber that may be closer to the piston side along the axis may havesmaller diameters than locations that may be closer to the injectionside along the axis. Optionally, the injection chamber may becylindrical such that the cross-sectional size remains the same atdifferent locations along the axis. In other embodiments, the injectionchamber may be conical or fluted such that different locations of theinjection chamber that may be closer to the piston side along the axismay have smaller diameters than locations that may be closer to theinjection side along the axis.

The body also may include an outward facing surface 916 that may bedistal from the axis. For example, the inward facing surface may beproximal to the axis and the outward facing surface may be distal to theaxis in that the inward facing surface may be closer to the axis thanthe outward facing surface.

The body has plural channel surfaces 918 that may define two or more gaschannels 912, 920 located between the injector side and the piston sideof the body. The gas channels may extend through the body from theoutward facing surface through the inward facing surface. In variousembodiments, some channel surfaces form linear slots through the body asgas channels, while some other channel surfaces form circular channelsthrough the body as the gas channels. The slots may be elongated indirections extending from one side, or toward an opposite side. In otherembodiments, the slots may be elongated in other directions and/or mayhave another shape. For example, the slots may be curved, may be arched,may be formed from two or more differently oriented linear portions, orthe like. In one embodiment, the channel surfaces and/or gas channelsmay have another size and/or shape. As shown in FIG. 12, for example,surfaces may be undulating surfaces. The channels do not appear toextend to the outward facing surface of the body in FIG. 12 due to thechannels extending along directions that may be angled downward in FIG.11. The selection of the direction and shape may be based on the desiredend use, the type of engine and fuel(s), and other application specific

In the illustrated embodiment, mixture conduits 922 may be defined by,or disposed between, the gas channels. The mixture conduits 922 areinclude interior channel surfaces 924 inside the body of the assembly900. The gas channels 920 may be disposed between the mixture conduits922 and the injector surface 908, and the gas channels 912 may bedisposed between the mixture conduits 922 and the piston surface 910.

In some embodiments, the one or more of the surfaces may have acatalytic coating, wear resistance coating, or carbon buildup resistantcoating. Additionally, or alternatively, the surface may be treated.Suitable treatments may include plasma treatment, heat treatment, lasercladding, nitriding, carbonizing, and the like.

Each of the conduits or channels extends from an entry port or openingto an opposite exit port or opening. The entry ports for the gasconduits or channels may be located along the outward facing surface ofthe body as the gases may be received into the conduits or channelsthrough the ports in the outward facing surface. The exit ports for thegas conduits or channels may be located along the inward facing surfaceof the body as the gases exit from the conduits or channels through theports in the inward facing surface. The entry ports for the mixtureconduits may be located along the inward facing surface of the body asthe mixture may be received into the conduits through the ports in theinward facing surface. The exit ports for the conduits may be locatedalong the outward facing surface of the body as the mixture exits fromthe conduits through the ports in the outward facing surface.

The entry and/or exit ports of the inlets and/or outlets of the channelsand/or conduits may have rounded shapes along edges of the channels orconduits defined by the interfaces between the definitional surfaces andthe outward facing surface, for example as shown in FIGS. 9 and 11. Inone embodiment, these edges may have a non-rounded shape, such as aninety-degree interface between the definitional surfaces and theoutward facing surface. The rounded edges may allow for more gases toflow into the channels and/or may provide for increased surfaceinteraction (and therefore more heat transfer) between the body and thegases. Optionally, the entry and/or exit ports of the channels may haveconical shapes that decrease in cross-sectional area in locations in thechannels that may be farther from the outward facing surface.Optionally, the entry and/or exit ports of the channels may have flutedshapes that increase in cross-sectional area in locations in thechannels that may be farther from the outward facing surface. In oneembodiment, the exit port is configured to anchor a flame front at adetermined location. As an example, a flame holder may be disposed atthe exit port. The flame holder may anchor the flame front in adetermined location during combustion.

The channels optionally may include one or more structures or featuresthat change the flow of gases in the channels. For example, the channelsurfaces may be undulating surfaces that define one or moreprotuberances and/or dimples that extend out of or into the body insidethe air channels. In one embodiment, the channel surfaces may be smoothor flat surfaces that do not include protuberances or dimples. Theundulating shape of the surfaces create non-linear (e.g., undulating)pathways as the channels for the gases to flow into the injectionchamber of the body. Non-linear pathways may be curved, have a sawtoothor zig-zag shape, or the like. The non-linear pathways in which thegases flow into the interior chamber may increase the surface area ofthe body that contacts the gases and/or may increase the dwell time thatthe gases may be in contact with the body inside the channels. This mayincrease the transfer of heat from the gases to the body (relative tolinear pathway channels). The body has conduit surfaces that definefuel-and-gas mixture conduits extending through the body. These conduitsurfaces may be elongated in directions that form acute angles with thecenter axis, as shown in FIG. 11. For example, one or more of thechannels may have a turbulator, turbulator vane, or guide vane at one ormore of the entry ports to change the flow of the gases into thechannels. These structures may be used to achieve a desired flowdistribution into the channels. Features such as protuberances anddimples may also be incorporated inside the flow channels to increasemixing and/or enhance heat transfer.

In the illustrated embodiment, each of the conduits or channels may beelongated in a direction that may be non-orthogonally angled withrespect to the axis. For example, the inlets or entry ports of the gaschannels may be located closer to the piston side of the body than theinjector side of the body, and the exit ports of the gas channels may belocated closer to the injector side of the body than the piston side ofthe body. The entry ports of the mixture conduits may be located closerto the injector side of the body than the piston side of the body, andthe exit ports of the mixture conduits may be located closer to thepiston side of the body than the injector side of the body. The channelsmay be aligned with the central axis of the fuel that is being injected.

In operation, one or more streams of fuel may be injected into thecentral volume by fuel injector(s) via an upper aperture or opening1004. The flow of the fuel into the central volume draws gases into thecentral volume via the gas channels. The gases flow into the centralvolume and mix with the fuel in the central volume to form thefuel-and-gas mixture at a defined ratio (of fuel to air). In oneembodiment, all or substantially all the gases that mix with the fuel toform the fuel-and-gas mixture flows into the central volume via thechannels, and not through the upper aperture of the central volume. Thefuel-and-gas mixture then flows out of the central volume through theconduits and into the combustion chamber of the engine cylinder.

The angles at which the conduits may be oriented relative to the centeraxis may be changed in different bodies to control how far the mixturepenetrates into the combustion chamber of the engine cylinder. Forexample, if the mixture spray flowing through a conduit is directed toimpinge on one or more surfaces of the channels, there may be a momentumexchange between the mixing structure and the mixture spray. This candecrease the momentum of the mixture spray and decrease how far themixture penetrates the combustion chamber of the engine cylinder. In oneembodiment, the conduits may be elongated along directions that coincidewith (e.g., may be linearly aligned with) the directions in which thefuel streams may be directed into the central volume by the fuelinjector. For example, the exit or outlet ports of the conduits may bealigned with apertures of a fuel injector through which streams of fuelmay be directed. This may provide for maintaining more of the momentumof the fuel streams (e.g., the fuel) into and through the conduits (asthe mixture), and into the combustion chamber. Additionally, this mayprovide for streams of the mixture to flow through the conduits inlocations that may be more centered along central axes of the conduits(compared to the conduits not being aligned with the fuel injectorapertures). Optionally, the entry ports of the conduits may include arestricting structure, such as a lip, ring, or the like, that reducesthe cross-sectional area of the entry port of a conduit relative to thecross-sectional area of the same conduit in other locations. Thisrestricting structure may assist with centering the flow of the mixturein the conduit.

Centering the streams of the mixture in the conduits may provide formaintaining more of the momentum of the mixture exiting the conduits(compared to the conduits not being aligned with the fuel injectorapertures). In one embodiment, the conduits may be elongated indirections that may be angled (e.g., not parallel to) the directions inwhich the streams of fuel may be injected into the central volume. Thismay decrease the momentum of the fuel into the conduits and/or decreasethe momentum of the mixture out of the conduits. Because the momentum ofthe mixture heading out of the conduits may control or impact how muchsoot may be oxidized in the combustion chamber, changing the angles ofthe conduits in different bodies may control how much soot may beoxidized.

Various aspects of the conduits and/or the exit ports of the conduitsmay be modified relative to the embodiment shown in FIGS. 9 through 11.For example, the cross-sectional shape or size of the conduits maydiffer at different locations along the length of the conduits. Forexample, the conduits may have conical shapes (instead of theillustrated cylindrical shapes) that decrease in cross-sectional area inlocations that may be farther from the inward facing surface of thebody. The exit ports of the conduits may have turbulator vanes or otherstructures to change the flow of the mixture exiting the conduits. Thismay help focus or direct the mixture farther into the combustion chamberof the engine cylinder. The exit ports of the conduits may have arestriction structure (e.g., a lip) that urges or focuses the streams offuel-and-gas mixtures closer together. Optionally, the exit ports of theconduits may have dimples to change the flow of the mixture out of theconduits and/or to decrease the likelihood of the conduits becomingplugged at the exit ports. For example, the dimples may provide volumesthat may become filled with soot or the like prior to clogging the exitports. This may extend the useful life of the conduits.

In one embodiment, the surfaces of the mixture conduits may be smoothand do not have protuberances or dimples. This may allow for thefuel-and-gas mixture that exits out of the body via the mixture conduitsto have faster flow and/or greater momentum upon exiting the body(compared to mixture conduits that may be not smooth or haveundulations). The mixing structure directs the fuel-and-gas mixtures todesired locations within the combustion chamber to facilitate theoxidation of soot.

Non-smooth surfaces of the gas channels may cause the flow of the gasesto change and become more turbulent. A turbulent flow may increase thehomogeneity of the mixture flowing therethrough. For example, theundulating surfaces may create spin, swirl, and/or turbulence in theflow of gases, which also may create spin, swirl, and/or turbulence inthe flow of the mixture in the central volume. The gases and/or mixturescan spin when the gases and/or mixtures predominantly move around acenter axis or direction, such as when the majority of mass and/or flowof the gases and/or mixtures are spinning around the same axis ordirection. The gases and/or mixtures can swirl when the gases and/ormixtures predominantly (e.g., a majority of the mass and/or flow) movein a spiral pattern around the axis or direction. The movement gasesand/or mixtures can have turbulence when the gases and/or mixtures donot predominantly move in the same direction, whether that direction bea swirling, spinning, or linear movement. The gases flow into thecentral volume and mix with the fuel in the central volume to form thefuel-and-gas mixture at a defined ratio (of fuel to gas). Thenon-uniform flow of the gases may assist with the mixing of the fuelrelative to having smooth surfaces around the gas channels.

Optionally, the undulating shape of the surfaces increase the surfacearea of the body to which the incoming gases contact as the gases flowinto the central volume. Increasing the surface area that contacts thegases may increase how much thermal energy may be drawn or transferredfrom the gases to the body relative to flat or smooth surfaces. As aresult, the gases may be cooled by a greater amount. The inward facingsurface of the body may define undulating surfaces, protuberances,and/or dimples to create spin in the flow of gases, fuel, and/or themixture in the central volume.

For a given engine cylinder at a given operating condition, the sizes(e.g., diameters or surface areas) of the conduits, and/or centralvolume, the shapes of the conduits, and/or central volume, the lengthsof the conduits, the presence or absence of undulations in surfaces, thenumber of the conduits, and/or the angles at which the conduits may beoriented relative to the axis may be modified to change the ratio offuel to gas in the mixture or the degree of homogeneity and dispersionof fuel to gas that may be output from the mixing structure. Changingone or more of these parameters may change how much fuel may be in themixture, how much gas may be in the mixture, how quickly the mixtureleaves the mixing structure, how far the mixture penetrates into thecombustion chamber of the cylinder, the direction or angle of thedeparting flow, and the like.

The injector surface of the body may include one or more alignment holesor keying features 902 to align the mixture conduits with directions inwhich the fuel streams may be directed into the central volume of thebody. These keying features may be holes or other receptacles thatreceive complementary keying features (e.g., pins) connected with thecylinder head. Placing the pins into the holes may ensure that the fuelstreams coming from the fuel injector may be directed into the mixtureconduits. In particular, the alignment of the nozzles of the injectorwith the center of the corresponding mixing conduit may be ensured.

Optionally, the inward facing surface of the body may include one ormore textured or undulating surfaces, protuberances, and/or dimples.These undulating or textured surfaces, protuberances, and/or dimples mayassist with changing the direction in which fuel and/or gases flow andmix the fuel and gas to a defined mixing level and/or ratio. The inwardfacing surface may have a conical or fluted shape to assist with mixingthe fuel with the gases in the central volume. For example, thecross-sectional area of the volume in planes that may be perpendicularto the axis may be larger near the injector side and smaller near thepiston side. This decreasing cross-sectional area of the volume may mixand concentrate the fuel in the mixture prior to the mixture flowing outof the volume via the conduits.

In one embodiment, one or more of the structures forming the body mayinclude cooling conduits extending through the interior portions of thestructures. These cooling conduits may be fluidly coupled with a sourceof a cooling or working fluid, such as cooled air, a liquid coolant, orthe like. Suitable coolants may include air, water, oil, and the like.These cooling conduits may not be fluidly coupled with the gas channelsor mixture conduits to prevent contamination of the fuel, gases, and/ormixture. The mixing structure can be liquid cooled using coolant fromthe cylinder head or piston, depending on where the mixing structure ismounted. Optionally, the mixing structure can be cooled throughconduction to the component that the mixing structure is mounted to. Thecooling or working fluid may flow through the cooling conduits to helpcool the body and increase the thermal transfer between the gases andthe body.

FIG. 13 illustrates a side view of another embodiment of a mixingstructure 1300. The mixing structure may include a body 1304 thatdefines an axis 1306 and that extends from an injector side 1308 towardan opposite piston side 1310 along the axis. The body may include acylinder head interface structure or portion 1326 and a thermalmanagement structure 1314. The cylinder head interface structure coupleswith a cylinder head, while the thermal management structure faces acrown of a piston. The interface structure of the body is press fit intoplace into a receiving cavity of the cylinder head. Other suitablecoupling methods may include having the insert welded, bolted to, orformed as part of a cylinder head of an engine cylinder. FIG. 14illustrates a perspective view of an injector side of the mixingstructure shown in FIG. 13.

In one embodiment, the body symmetrically extends around or encirclesthe center axis. In another embodiment, the axis may not extend alongthe center of the body and/or the body may not be symmetric around orabout the axis. The injector side of the body faces a fuel injector ofan engine cylinder while the piston side of the body faces a piston headof the engine cylinder.

The body has an inward facing surface 1400 proximate to the center axis.This inward facing surface defines one or more central volumes 1402inside the body. While only a single central volume may be shown inFIGS. 13 and 14, in one embodiment, the body may include one or moreinternal walls or other structures that divide the single central volumeinto two or more smaller volumes. The volume may be referred to as aninjection chamber. The injection chamber volume may have a shape thatdecreases in cross-sectional size in locations that may be farther fromthe injector side of the body. Optionally, the injection chamber volumemay be cylindrical such that the cross-sectional size remains the sameat different locations along the central axis or may be conical orfluted.

The body also may include an outward facing surface 1316 that may bedistal from the central axis. The body has channel surfaces 1318 thatdefine gas channels 1320 located between the injector side and thepiston side of the body. The gas channels extend through the body fromthe outward facing surface through the inward facing surface. In theillustrated embodiment, the gas channel surfaces form linear slotsthrough the body as the gas channels. The slots may be elongated indirections extending from one side or toward the opposite side. In otherembodiments, the slot may be elongated in other directions and/or mayhave another shape. For example, the slots may be curved, may be arched,may be formed from two or more differently oriented linear portions, orthe like. The surfaces may be undulating surfaces, flat surfaces, othercurved surfaces, or the like.

In the illustrated embodiment, the mixture conduits may be disposedbetween the gas channels. For example, the gas channels may beinterspersed within the mixture conduits such that there may be one gaschannel between neighboring pairs of the mixture conduits.

The body has conduit surfaces that define fuel-and-gas mixture conduitsextending through the body. These conduit surfaces may be elongated indirections that form acute angles with a center axis. The conduitsurfaces may be smooth surfaces that do not include undulations,protuberances, or dimples. In another embodiment, the conduit surfacesmay have undulations, protuberances, and/or dimples.

Each of the conduits or channels extends from an entry port or openingto an opposite exit port or opening, as described above in connectionwith the mixing structure. The entry and/or exit ports of the channelsmay have rounded shapes along edges of the channels. In one embodiment,these edges may have a non-rounded shape. The rounded edges may allowfor more gases to flow into the channels and/or may provide forincreased surface interaction (and therefore more heat transfer) betweenthe body and the gases. Optionally, the entry and/or exit ports of thechannels may have conical shapes or fluted shapes.

In the illustrated embodiment, each of the conduits or channels may beelongated in a direction that may be non-orthogonally angled withrespect to a central axis. For example, the entry or entry ports of thegas channels may be located closer to the piston side of the body thanthe injector side of the body, and the exit ports of the gas channelsmay be located closer to the injector side of the body than the pistonside of the body. The entry ports of the mixture conduits may be locatedcloser to the injector side of the body than the piston side of thebody, and the exit ports of the mixture conduits may be located closerto the piston side of the body than the injector side of the body.

In operation, one or more streams of fuel may be injected into thecentral volume by fuel injector(s) via an upper aperture or opening1404. The flow of the fuel into the central volume draws gases into thecentral volume via the gas channels. The gases flow into the centralvolume and mix with the fuel in the central volume to form thefuel-and-gas mixture at a defined ratio. In one embodiment, all orsubstantially all the gases that mix with the fuel to form thefuel-and-gas mixture flows into the central volume via the channels, andnot through the upper aperture of the central volume. The fuel-and-gasmixture flows out of the central volume through the conduits and intothe combustion chamber of the engine cylinder.

The angles at which the conduits may be oriented relative to the centeraxis may be changed in different bodies to control how far the mixturepenetrates into the combustion chamber of the engine cylinder, asdescribed above. In one embodiment, the conduits may be elongated alongdirections that coincide with the directions in which the fuel streamsmay be directed into the central volume by the fuel injector.Optionally, the entry ports of the conduits may include a restrictingstructure that reduces the cross-sectional area of the entry port of aconduit relative to the cross-sectional area of the same conduit inother locations, as described above.

In one embodiment, the conduits may be elongated in directions that maybe angled (e.g., not parallel to) the directions in which the streams offuel may be injected into the central volume. This may decrease themomentum of the fuel into the conduits as the mixture and/or decreasethe momentum of the mixture out of the conduits.

Various aspects of the conduits and/or the exit ports of the conduitsmay be modified from the illustrated embodiments. For example, thecross-sectional shape or size of the conduits may differ at differentlocations along the length of the conduits. For example, the conduitsmay have conical shapes (instead of the illustrated cylindrical shapes)that decrease in cross-sectional area in locations that may be fartherfrom the inward facing surface of the body. This may help direct themixture into desired location within the combustion chamber of theengine cylinder. The exit ports of the conduits may have a restrictionstructure (e.g., a lip) that urges or blends the streams of mixturescloser together. Optionally, other conduit exit ports may have dimples,grooves or textures that may change the flow of the mixture out of theconduits and/or to decrease the likelihood of the conduits becomingplugged at the exit ports.

In one embodiment, the surfaces of the mixture conduits may be smoothand do not have protuberances or dimples. In another embodiment, thesurfaces may include protuberances and/or dimples. The inward facingsurface of the body may include undulating surfaces, protuberances,and/or dimples to create turbulence in the flow of gases, fuel, and/orthe mixture in the central volume. The sizes (e.g., diameters or surfaceareas) of the conduits and/or central volume, the shapes of the conduitsand/or central volume, the lengths of the conduits the presence orabsence of undulations in surfaces the number of the conduits and/or theangles at which the conduits may be oriented relative to the axis may bemodified to change the ratio of fuel to gas in the mixture that may beoutput from the mixing structure, as described above.

Optionally, the inward facing surface of the body may include one ormore undulating surfaces, protuberances, and/or dimples, as describedabove. The inward facing surface may have a conical or fluted shape toassist with mixing the fuel with the gases in the central volume, asdescribed. In one embodiment, one or more of the structures forming thebody may include cooling conduits extending through the interiorportions of the structures as described.

FIG. 15 illustrates a side view of another embodiment of a mixingstructure 1500. The center axis defined by a body 1504 is concentricwith the body that symmetrically extends around or encircles the axis1506. In another embodiment, the axis does not extend along the centerof the body but rather is asymmetric relative to the axis. The injectorside of the body faces a fuel injector of an engine cylinder while thepiston side of the body faces a piston head of the engine cylinder. FIG.16 illustrates a perspective view of an injector side 1508 of the mixingstructure shown in FIG. 15.

The mixing structure may include the body that defines a central axisand that extends from an injector side toward an opposite piston side1510 along the axis. The body may include a cylinder head interfacestructure or portion 1526. The cylinder head interface structure coupleswith a cylinder head, while the thermal management structure faces acrown of a piston. The interface structure of the body can be welded orotherwise attached to a cylinder head of an engine cylinder in variousembodiments. The body has an outward facing surface 1516 that may bedistal from the axis. The body has channel surfaces 1518 that define gaschannels 1520 located between the injector side and the piston side ofthe body. The gas channels extend through the body from the outwardfacing surface through the inward facing surface. The body also has athermal management structure 1514. In various other embodiments, theinward facing surface of the body may include undulating surfaces,protuberances, and/or dimples, as described above, or may be smooth.

The body has an inward facing surface 1400 proximate to the axis. Thisinward facing surface defines one or more central volumes 1602 insidethe body into which an injector injects liquid fuel. In this embodiment,the body may include one or more internal walls or other structures thatdivide the single central volume into two or more smaller volumes. Theinjection volume optionally may be referred to as an injection chamber.The injection volume may have a shape that decreases in cross-sectionalsize in locations that may be farther from the injector side of thebody. In other embodiments, the injection volume may be cylindrical suchthat the cross-sectional size remains the same at different locationsalong the axis or may be conical or fluted.

In the illustrated embodiment, the interfaces between the channelsurfaces 1518 and the outward facing surface 1516 form arched edges1501, with ends of each arch edge connected by a straight edge 1503. Thechannel surfaces forming gas channels decrease in size from the outwardfacing surface to the inward facing surface of the body. In variousembodiments the entry ports of the gas channels may be significantlylarger at the outward facing surface 1516 of the body than the exitports of the gas channels at the inward facing surface of the body. Thegas channels may be funnel shaped, as in the illustrated example, withthe gas channels rapidly reducing in size from large entry ports totriangular exit ports. The channel surfaces may be selected based onapplication specific requirements, and as such may be undulatingsurfaces, flat surfaces, other curved surfaces, or the like.

In the illustrated embodiment, the mixture conduits may be interposedbetween the gas channels. For example, the gas channels may beinterspersed within the mixture conduits such that there may be one gaschannel between neighboring pairs of the mixture conduits. These conduitsurfaces may be elongated in directions that form acute angles with thecenter axis. One or more of the surfaces may have a catalytic coating orcarbon buildup resistant coating. In various embodiments, the channelsoptionally may include one or more structures that change the flow ofgases in the channels.

During engine operation, one or more streams of fuel may be injectedinto the central injection volume by fuel injector(s) via an upperaperture or opening 1604. The flow of the fuel into the centralinjection volume draws gases into the central injection volume via theair channels. The gases flow into the central injection volume and mixeswith the fuel in the central injection volume to form the fuel-and-gasmixture. In one embodiment, all or substantially all the gases that mixwith the fuel to form the fuel-and-gas mixture flows into the centralinjection volume via the channels, and not through the upper aperture ofthe central injection volume. The fuel-and-gas mixture then flows out ofthe central injection volume through the mixture conduits and into thecombustion chamber of the engine cylinder.

Various aspects of the conduits and/or the exit ports of the conduitsmay be modified from the embodiments shown herein. For example, thecross-sectional shape or size of the conduits may differ at differentlocations along the length of the conduits. Suitable conduits may haveconical shapes (instead of the illustrated cylindrical shapes) thatdecrease in cross-sectional area in locations that may be farther fromthe inward facing surface of the mixing structure body. This may helpcontrol the distribution of the mixture flow into the combustion chamberof the engine cylinder.

The sizes (e.g., diameters or surface areas) of the conduits and/orcentral injection volume, the shapes of the conduits and/or centralinjection volume, the lengths of the conduits, the presence or absenceof undulations in surfaces, the number of the conduits, and/or theangles at which the conduits may be oriented relative to the axis andmay be selected based on a desired ratio of fuel to gases in the mixturethat may be output from the mixing structure, as described above.

FIG. 17 illustrates a side view of another embodiment of a mixingstructure 1700. The mixing structure may include a body 1704 thatdefines an axis 1706 and that extends from an injector side 1708 towardan opposite piston side 1710 along the axis. The body may include acylinder head interface structure or portion 1726 and a thermalmanagement structure 1714. The cylinder head interface structure coupleswith a cylinder head, while the thermal management structure faces acrown of a piston.

In one embodiment, the axis may be a center axis that the bodysymmetrically extends around or encircles. In one embodiment, the axismay not extend along the center of the body and/or the body may not besymmetric around or about the axis. The injector side of the body facesa fuel injector of an engine cylinder while the piston side of the bodyfaces a piston head of the engine cylinder. The body also may include anoutward facing surface 1716 that may be distal from the axis. The bodyhas channel surfaces 1718 that define gas channels 1720 located betweenthe injector side and the piston side of the body.

Channel surfaces 1722 form mixture conduits 1724 that increase in sizefrom the inward facing surface of the body to the outward facing surfaceof the body. In the illustrated embodiment, the mixture conduits may bedisposed between the gas channels. A single mixture conduit may bedisposed between one pair of the gas channels and another pair of thegas channels. In another embodiment, a single gas channel or more thantwo gas channels may be on each side of each mixture conduit. Eachmixture conduit may be significantly larger than each gas channel and/ora combination of two gas channels.

FIG. 18 illustrates a perspective view of the injector side of themixing structure shown in FIG. 17. While only a single central volume isshown in FIGS. 17 and 18 in other embodiments a body may include one ormore internal walls or other structures that divide the single centralvolume into two or more smaller volumes. The body has an inward facingsurface 1800 proximate to the axis. This inward facing surface definesone or more central volumes 1802 inside the body. The single centralvolume may be referred to as an injection chamber. The single centralvolume may have a shape that decreases in cross-sectional size inlocations that may be farther from the injector side of the body. Also,in other embodiments, the single central volume may be cylindrical suchthat the cross-sectional size remains the same at different locationsalong the axis or may be conical or fluted.

The interfaces between the channel surfaces and the outward facingsurface form elongated slots as the gas channels. The channel surfacesmay be undulating surfaces that form undulating gas channels, similar tothe gas channels shown in FIG. 9.

In operation, one or more streams of fuel may be injected into thecentral volume 1802 by fuel injector(s) via an upper aperture or opening1704. The flow of the fuel into the central volume draws gas into thecentral volume via the gas channels. The gas flows into the centralvolume and mixes with the fuel in the central volume to form thefuel-and-gas mixture at a defined ratio. In one embodiment, all orsubstantially all the gases that mix with the fuel to form thefuel-and-gas mixture flows into the central volume via the channels, andnot through the upper aperture of the central volume. The fuel-and-gasmixture then flows out of the central volume through the conduits andinto the combustion chamber of the engine cylinder.

FIG. 19 illustrates a side view of another embodiment of a mixingstructure 1900. The mixing structure has a body 1904 that defines thegas channels and the mixture conduits. This mixing structure differsfrom other mixing structures in that it does not include the additionalgas channels, such as shown in FIG. 9. FIG. 20 illustrates a perspectiveview of an injector side 1908 of the mixing structure shown in FIG. 19.

The mixing structure 1900 also differs from the mixing structure 900 inthat the mixing structure 1900 may include a step portion feature 1901projecting upward from the body 1904 (e.g., toward the fuel injectorwhen the mixing structure 1900 may be installed). The step portionfeature 1901 may include a portion of the body 1904 in a cylinder headinterface structure 1914 of the body 1904 that extends toward the fuelinjector. The step portion feature 1901 may engage the cylinder head tofurther separate the mixture conduits from the fuel injector withoutinterfering with operation of valves of the cylinder head (e.g., withoutcontacting the valves).

FIG. 21 illustrates a side view of another embodiment of a mixingstructure 2100. FIG. 22 illustrates a perspective view of an injectorside 2108 of the mixing structure 2100 shown in FIG. 21. The mixingstructure 2100 may be similar to the mixing structure 1900 in that themixing structure 2100 may include a body 2104 having the gas channelsand the mixture conduits.

The mixing structure 2100 differs from the mixing structure 1900 in thatthe mixing structure 2100 may include a step portion feature 2101projecting upward from the body 2104. The step portion feature 2101 haslarger circumference or cross-sectional area than the step portionfeature 1901. The step portion feature 2101 may engage the cylinder headto further separate mixture conduits 2124 from the fuel injector withoutinterfering with operation of valves of the cylinder head (e.g., withoutcontacting the valves).

The mixing structure 2100 also differs from the mixing structure 900 inthat the mixture conduits 2124 in the structure 2100 have a largerdiameter or cross-sectional size, and/or may be shorter in length. Themixture conduits 2124 may direct the fuel-and-gas mixture into thecombustion chamber of an engine cylinder but may be larger to controlhow the mixture may be delivered into the combustion chamber.

The mixing structures described above may have a sealed piston side thatdoes not include any openings for fuel to exit the interior volume, thegases to enter the interior volume, or the mixture to exit the interiorvolume. The only openings in one or more embodiments of the mixingstructures described above may be in the outward facing sides and theinjector sides of the mixing structures.

In one embodiment, one or more of the mixing structures described abovemay have an opening or aperture in the piston side. FIG. 23 illustratesa perspective view of an alternative embodiment of the piston side ofthe mixing structure 900 shown in FIGS. 9 through 12. As shown, thepiston side may have an aperture 2300 through the piston side. Thisaperture 2300 may allow gases to enter into the central volume of themixing structure 1002 through the piston side of the mixing structure900. Allowing gases to enter in this way may balance the gases enteringthe central volume through the gas channels with the inward flow ofgases into the central volume through the aperture 2300. This balancingmay help to center the streams of the fuel-and-gas mixtures in thecenters of the mixture conduits. For example, with the gases onlyentering the central volume via the gas channels, turbulence may becreated in the central volume, which may prevent or disrupt the flow ofthe mixture through the center paths of the mixture conduits. Providingthe aperture 2300 may balance the flow of the gases and center themixture flow in the mixture conduits.

Various aspects of the gas channels, mixture conduits, entry ports,and/or exit ports may be modified from the embodiments shown herein. Forexample, the cross-sectional shape or size of the channels, conduits,and/or ports may differ from the illustrated embodiments to produce adesired or predetermined fuel-to-gas ratio of the mixture. As oneexample, the mixture conduits may have conical shapes (instead of theillustrated cylindrical shapes) that decrease in cross-sectional area inlocations that may be farther from the inward facing surface of themixing structure body. This may help direct the mixture flow fartherinto the combustion chamber of the engine cylinder.

Various embodiments of the mixing structures may receive apost-injection of fuel and direct this post-injection fuel into thecombustion chamber of the engine cylinder via the mixture conduits. Thepost-injection fuel may be provided by the fuel injector subsequent to aprevious fuel injection that may be used for combustion in the enginecylinder. The post-injection fuel may mix with gases in the centralvolume of the mixing structure to form the mixture, which may then bedirected into the combustion chamber of the engine cylinder via themixture conduits of the mixing structure. This additional mixture mayfurther oxidize soot inside the combustion chamber of the enginecylinder.

In one embodiment, a control system of an engine having one or more ofthe mixing structures installed between a fuel injector and a pistoncrown may automatically detect whether gas channels and/or mixtureconduits of a mixing structure may be clogged and/or whether the mixingstructure may be misaligned (e.g., the mixture conduits may be notaligned with the fuel streams from the fuel injector). The controlsystem may include one or more processors (e.g., one or moremicroprocessors, field programmable gate arrays, integrated circuits, orthe like) that monitor the power or emissions output by the engineand/or by each cylinder of the engine. Responsive to determining that anengine cylinder may be misfiring, knocking, or producing less horsepowerthan other cylinders in the same engine, the control system maydetermine that a gas channel and/or mixture conduit of a mixingstructure associated with that cylinder may be clogged, or that themixing structure may be misaligned. The control system may provideoutput to an operator of a powered system that includes the engine (suchas a vehicle), such as a visual, audible, or other notification that themixing structure may need repair, replacement, or further inspection.

The presence of one or more embodiments of the mixing structures mayreduce the need for skip firing operation of engines. Skip firing mayinvolve the fuel injector providing fuel to some, but not all,combustion cycles of an engine cylinder. For example, the fuel injectormay only direct fuel into the central volume of a mixing structureduring every other engine rotation (instead of for each enginerotation). Use of the mixing structures in engines may reduce the needfor skip firing of some engines. For example, addition of the mixingstructures to an engine may eliminate a previous need to use skip firingto operate the engine. The presence of one or more embodiments of themixing structures may reduce the need for operating at higher fuelinjection pressures, the need for using aftertreatment systems, and/orthe need for using multiple fuel injections to control emissions.

The control system of a vehicle may base the timing of engine operationresponsive to mixing structures being positioned between fuel injectorsand piston crowns of engine cylinders and based on the load placed onthe engine. For example, as the engine load increases (e.g., responsiveto the throttle being opened more), increased amounts of fuel may beinjected into the central volumes of the mixing structures.Consequently, increased amounts of gases may need to be drawn into thecentral volumes of the mixing structures to pre-mix with the fuel tomaintain the fuel-to-gas ratio of the mixture. The control system maychange the engine cylinder timing to allow for a longer time for more ofthe gases to enter into the central volumes responsive to increases inthe engine load. For example, the control system may direct the fuelinjectors to begin injecting fuel into the central volumes at an earliertime in the engine cycle. Conversely, the control system may change theengine cylinder timing to reduce the time for gases to enter the centralvolumes responsive to decreases in the engine load.

FIG. 24 illustrates a perspective view of part of another embodiment ofa mixing structure 2400. The mixing structure has a body that can bepositioned between a fuel injector and a piston head, as describedabove. This body can include the center aperture or chamber where gasand fuel are mixed before being directed into the combustion chamber ofan engine cylinder, also as described above. One difference between themixing structure shown in FIG. 24 and the other mixing structures isthat the mixing structure in FIG. 24 includes mixture conduits 2402 thatoverlap with gas channels 2404. Similar to the gas channels describedabove, the gas channels in FIG. 24 can be passages through which gas isdrawn into the interior of the body of the mixing structure to mix withfuel injected into the interior of the body by one or more fuelinjectors. This gas is entrained into the fuel spray from the fuelinjector(s) to form a fuel-and-gas mixture. The mixture conduits shownin FIG. 24 direct sprays of the fuel-and-gas mixture out of the mixingstructure and into the combustion chamber of the engine cylinder. Themixture conduit overlaps with the gas channels in that at least part2406 of one or more of the gas channels extend through the mixtureconduits, as shown in FIG. 24.

In an embodiment, a mixing structure (e.g., for mixing fuel and gas inan engine) includes a body that defines an axis and extends from aninjector side toward an opposite piston side along the axis. The bodyhas an inward facing surface proximate to the axis that defines acentral volume and an outward facing surface distal from the axis. Theinjector side of the body is configured to face a fuel injector of acylinder of an engine while the piston side of the body is configured toface a piston head of the engine cylinder. The body has one or morechannel surfaces that define one or more gas channels extending throughthe body to and from the central volume. The body has one or moreconduit surfaces that define one or more fuel-and-gas mixture conduitsextending through the body to and from the central volume. There may beplural conduits and plural channels, both of which are radiallysymmetrically distributed around the axis. The central volume isconfigured to receive one or more streams of fuel from the fuelinjector, and one or more streams of gas from the one or more gaschannels. The central volume, channel(s), and/or conduit(s) areconfigured such that during operation of the engine, at least one of thestreams of the fuel are mixed with the one or more streams of gas toform a fuel-and-gas mixture at a designated ratio of fuel to gas. Thefuel-and-gas mixture conduits are configured to direct the fuel-and-gasmixture out of the body and into a combustion chamber of the enginecylinder.

In an embodiment, an engine includes an engine block defining a cylinderwith a combustion chamber, a piston operably disposed in the cylinder, afuel injector, and a mixing structure. The fuel injector is positionedon a cylinder head side of the cylinder. The piston has a piston headwith a crown that faces the combustion chamber and fuel injector. Themixing structure is disposed between the piston and the fuel injector.The mixing structure includes a body that defines an axis and extendsfrom an injector side toward an opposite piston side along the axis. Thebody has an inward facing surface proximate to the axis that defines acentral volume and an outward facing surface distal from the axis. Theinjector side of the body faces the fuel injector while the piston sideof the body faces the piston head. The body has one or more channelsurfaces that define one or more gas channels extending through the bodyto and from the central volume. The body has one or more conduitsurfaces that define one or more fuel-and-gas mixture conduits extendingthrough the body to and from the central volume. There may be pluralconduits and plural channels, both of which are radially symmetricallydistributed around the axis. The central volume is configured to receiveone or more streams of fuel from the fuel injector, and one or morestreams of gas from the one or more gas channels (e.g., the gas receivedfrom the combustion chamber). The central volume, channel(s), and/orconduit(s) are configured such that during operation of the engine, atleast one of the streams of the fuel are mixed with the one or morestreams of gas to form a fuel-and-gas mixture at a designated ratio offuel to gas. The fuel-and-gas mixture conduits are configured to directthe fuel-and-gas mixture out of the body and into the combustion chamberof the engine cylinder. Thus, in operation, gas is entrained by theinjected fuel stream(s) from the combustion chamber through the gaschannels into the central volume of the body; by interaction between thegas and the channel surfaces (that define the gas channels), thermalenergy is transferred from the gas to the body (i.e., a temperature ofthe gas is reduced). The gas and fuel pass from the central volumethrough the fuel-and-gas mixture conduit(s) into the combustion chamber;the fuel-and-gas mixture conduit(s) serve to facilitate mixing of thegas and fuel prior to introduction into the combustion chamber. Atechnical effect is to improve the mixing of fuel and gas, and to reducethe temperature of mixed fuel and gas, prior to introduction into acombustion chamber (e.g., of a compression ignition engine), therebyreducing soot and other emissions. In embodiments, the fuel includesdiesel, and the gas includes ambient air. The gas may also includeambient air mixed with EGR. In an embodiment, the engine operates in afirst mode where the gas is ambient air only, and in a different, secondmode where the gas is a mixture of ambient air an EGR. The amount of EGRmay be static, or may be controlled to vary based on various engineand/or vehicle operating parameters.

In any of the embodiments herein, the body of the mixing structure maybe generally disc-shaped. That is, a generally round or circularstructure relative to the center axis. In embodiments, the injector sideof the body has a first diameter (defined by an outer periphery of theinjector side relative to a plane orthogonal to the axis), and thepiston side of the body has a second diameter that is larger than theinjector side (defined by an outer periphery of the piston side relativeto a plane orthogonal to the axis), with the two being concentricallyoriented such that a step is defined between the injector side and thepiston side.

In any of the embodiments set forth herein, an engine with one or moremixing structures may be positioned on board a vehicle, e.g., thevehicle has a chassis, hull, or other support platform, and a propulsionsystem (including the engine) for moving the vehicle. For example, theengine may drive a mechanical transmission, or the engine may drive analternator or generator for generating electrical power, which is usedto power, for example, one or more traction motors to propel thevehicle. Alternatively, the engine may be deployed as part of astationary or semi-stationary machine, such as a permanently installedor portable generator. In either case, the engine may be relativelylarge, e.g., it may have from 10-18 cylinders or more. In oneembodiment, an engine with one or more mixing structures is on board ahaul truck or other mining equipment, locomotive or other rail vehicle,or other off-highway vehicle; such a vehicle may be subject toparticular government regulations relating to production of soot andother engine emissions, where it may be desirable for the engine to haveone or more mixing structures as set forth herein to help meet thegovernment regulations.

In an embodiment, a kit of parts includes a mixing structure as setforth in any of the embodiments herein, and one or more hardware parts(e.g., adhesives, fasteners, adapters, etc.) that are configured for usein deploying the mixing structure inside an engine cylinder. The kit ofparts may also include a set of instructions (e.g., printed on paper orprovided electronically, such as on a website) that include pictures,diagrams, and/or text or other written indicia for explaining to atechnician how to outfit an engine cylinder with the mixing structure,such that the mixing structure operates as described herein. In anotherembodiment, a method of retrofitting an engine includes removing acylinder head, fuel injector, and/or other parts of or associated withan engine cylinder to expose the cylinder interior, operably attaching amixing structure as set forth in any of the embodiments herein to thefuel injector, cylinder, or piston, as applicable (for example, bywelding), and re-attaching any removed parts (e.g., the fuel injector orcylinder head) of the engine so that the engine is operable forcombusting fuel. The method may further include updating operatingsoftware of the engine, directly (e.g., by an operator accessing anon-board computer) or by remote wireless download or otherwise, tomodify operation of the engine to take into account the presence of themixing structure. For example, the engine may be operated at a leaner orricher fuel-gas mixture, relative to previous operation of the enginewithout the mixing structure. Each cylinder of a multi-cylinder enginemay be outfitted with its own, respective mixing structure. In oneembodiment, however, only a subset of plural engine cylinders (that is,less than all of the cylinders of an engine) are outfitted withrespective mixing structures. For example, it may be desirable to deploymixing structures only in donor cylinders, or only in non-donorcylinders, depending on the operation of the engine in question anddepending on where it is most needed or desired to reduce sootgeneration, for example. (Donor cylinder refers to a cylinder whoseexhaust is recirculated to the engine intake.)

In another embodiment, a method includes, with an engine controllerhaving one or more processors, controlling an engine to selectivelyindividually activate and deactivate one or more first cylinders of theengine, where the one or more first cylinders are outfitted withrespective mixing structures as set forth herein, and where at least oneor more second cylinders of the engine (which are different than thefirst cylinders) are not outfitted with mixing structures. For example,if some cylinders have mixing structures and some do not, the former canbe deactivated and the latter activated during times of operation whereit is not necessary to meet designated engine emissions levels, whereasthe former can be activated and the latter deactivated during times ofoperation where it is necessary to meet the designated engine emissionslevels. Or selective operation may be based on, for example, ambient airtemperatures (e.g., use of cylinders with the mixing structures may benot be needed or desired when air temp is below a designated threshold).

In one embodiment, a mixing structure is provided that includes a bodydefining an axis and extending from an injector side toward an oppositepiston side along the axis. The body has an inward facing surfaceproximate to the axis that defines a central volume and an outwardfacing surface distal from the axis. The injector side of the body isconfigured to face a fuel injector of a cylinder of an engine while thepiston side of the body is configured to face a piston head of theengine cylinder. The body has one or more channel surfaces that defineone or more gas channels extending through the body to and from thecentral volume. The body also has one or more conduit surfaces thatdefine one or more fuel-and-gas mixture conduits extending through thebody to and from the central volume. The central volume is configured toreceive one or more streams of fuel from the fuel injector, and one ormore streams of gas from the one or more gas channels. During operation,at least one of the streams of the fuel mixes with the one or morestreams of gas to form a fuel-and-gas mixture at a designated ratio offuel to gas. The fuel-and-gas mixture conduits are configured to directthe fuel-and-gas mixture out of the body and into a combustion chamberof the engine cylinder.

Optionally, the body can be a single, monolithic, seamless structure.The one or more gas channels can extend through the body such that thegas is drawn from outside of the body into the central volume of thebody. The designated ratio of the fuel-and-gas mixture can be controlledbased on at least one of a number, shape, location and size of one ormore of the gas channels or the mixture conduits. For example, to changethe designated ratio between different mixing structures, themanufacturer or modifier of a mixing structure can change the number,shape, location, and/or size of one or more gas channels and/or mixingstructures relative to another mixture conduit providing a fuel-and-gasmixture at another, different designated ratio of fuel to gas.

Optionally, the gas channels can have undulating shapes in the bodybetween the outward facing surface and the inward facing surface of thebody. Each of the mixture conduits can be configured to create spin,swirl, and/or turbulence in the fuel-and-gas mixture flowingtherethrough. The mixture conduits can extend radially outward from theaxis and are configured that each stream of the fuel-and-gas mixture iscentered in its corresponding mixture conduit.

The injector side of the body can define a step portion to avoid contactbetween the body and one or more inlet or outlet valves of the enginecylinder during operation of the engine. At least a portion of the bodycan be surface treated or coated.

In one embodiment, another mixing structure is provided. This mixingstructure includes a body configured to be positioned between a fuelinjector and a cylinder of an engine. The body defines an interiorvolume that is configured to receive gas from outside the body and toreceive one or more streams of fuel from the fuel injector in theinterior volume. The body also defines one or more mixture conduitsconfigured to conduct plumes of the fuel and gas, while mixing, from theinterior volume to one or more exit ports and therethrough to thecylinder.

Optionally, the body can be configured to cool the gas prior to orduring the mixture of the gas and the fuel in the interior volume andthe one or more mixture conduits. The body can have an interfacestructure that defines at least one alignment hole or an alignment pin.This interface structure can assist with aligning mixture conduits withnozzles of the fuel injector. The interface structure can be shrunk fit,press fit, welded, bolted to, threaded to, or formed as part of acylinder head of the engine cylinder.

The mixture conduits can define one or more apertures that connect toone or more gas channels and can be configured to direct flows of thegas from the one or more gas channels into the mixture conduit duringoperation of the cylinder. Each of the mixture conduits can include oneor more dimples, textured surfaces, grooves or protuberances tofacilitate mixing of the fuel and gas plumes flowing through the mixtureconduits. The mixture conduits can be configured to mix the fuel and gasto a homogeneous state prior to combustion of the plumes in thecylinder. The mixture conduits can be configured to direct the plumesinto the cylinder such that, relative to combustion in the cylinderwithout mixing the fuel and the gas to the homogeneous state, arelatively reduced amount or no amount of soot, nitrous oxides, or bothsoot and nitrous oxides are produced in the cylinder.

The body can have a step portion to extend a path length of the one ormore mixture conduits while avoiding contact of the body with one ormore valves of the engine cylinder.

In one embodiment, another mixing structure includes means forseparately receiving fuel from a fuel injector and receiving gas, meansfor mixing the fuel and the gas into a fuel-and-gas mixture at adesignated ratio, and means for directing the fuel-and-gas mixture intoa combustion chamber of an engine cylinder.

Optionally, the means for receiving the gas and the fuel cools the gasprior to or while the gas is mixing with the fuel. The means for mixingthe fuel and the gas into the fuel-and-gas mixture can include a mixtureconduit having inner walls and means for inducing turbulence into fueland gas streams to increase the homogeneity of the fuel-and-gas mixture,and means for centering and spacing a flow of the fuel-and-gas mixturefrom the inner walls of the mixture conduit.

Optionally, the means for directing the fuel-and-gas mixture into thecombustion chamber directs the fuel-and-gas mixture to penetrate intothe combustion chamber of the engine cylinder prior to combustion,delays the combustion of the fuel-and-gas mixture, or both directs thefuel-and-gas mixture into the combustion chamber of the engine cylinderprior to combustion and delays the combustion of the fuel-and-gasmixture.

As used herein, an element or step portion recited in the singular andproceeded with the word “a” or “an” should be understood as notexcluding plural of said elements or steps, unless such exclusion may beexplicitly stated. Furthermore, references to “one embodiment” of thepresently described subject matter may be not intended to be interpretedas excluding the existence of additional embodiments that alsoincorporate the recited features. Moreover, unless explicitly stated tothe contrary, embodiments “comprising” or “having” an element or aplurality of elements having a particular property may includeadditional such elements not having that property.

It may be to be understood that the above description may be intended tobe illustrative, and not restrictive. For example, the above-describedembodiments (and/or aspects thereof) may be used in combination witheach other. In addition, many modifications may be made to adapt aparticular situation or material to the teachings of the subject matterset forth herein without departing from its scope. While the dimensionsand types of materials described herein may be intended to define theparameters of the disclosed subject matter, they may be by no meanslimiting and may be exemplary embodiments. The scope of the subjectmatter described herein should, therefore, be determined with referenceto the appended claims, along with the full scope of equivalents towhich such claims may be entitled. In the appended claims, the terms“including” and “in which” may be used as the plain-English equivalentsof the respective terms “comprising” and “wherein.” Moreover, in thefollowing claims, the terms “first,” “second,” and “third,” etc. may beused merely as labels, and may be not intended to impose numericalrequirements on their objects. Further, any limitations of the followingclaims not explicitly written in means-plus-function format are not tobe interpreted based on 35 U.S.C. § 112(f), claim limitations expresslyusing the phrase “means for” followed by a statement of function invokethe 35 U.S.C. § 112.

This written description uses examples to disclose several embodimentsof the subject matter set forth herein, including the best mode, andalso to enable a person of ordinary skill in the art to practice theembodiments of disclosed subject matter, including making and using thedevices or systems and performing the methods. The patentable scope ofthe subject matter described herein may be defined by the claims, andmay include other examples that occur to those of ordinary skill in theart. Such other examples may be intended to be within the scope of theclaims if they have structural elements that do not differ from theliteral language of the claims, or if they include equivalent structuralelements with insubstantial differences from the literal languages ofthe claims.

What is claimed is:
 1. A mixing structure, comprising: a body definingan axis and extending from an injector side toward an opposite pistonside along the axis, the body having an inward facing surface proximateto the axis that defines a central volume and an outward facing surfacedistal from the axis, the injector side of the body is configured toface a fuel injector of a cylinder of an engine while the piston side ofthe body is configured to face a piston head of the engine cylinder, andthe body has undulating fins spaced apart from each other around theaxis of the body and around the central volume to define gas channelsradially extending through the body from outside of the body to thecentral volume, the undulating fins elongated in directions parallel tothe axis of the body, and the body has one or more conduit surfaces thatdefine one or more fuel-and-gas mixture conduits extending through thebody to and from the central volume, and the central volume isconfigured to receive one or more streams of fuel from the fuelinjector, and one or more streams of gas from the gas channels, andduring operation, at least one of the streams of the fuel mixes with theone or more streams of gas to form a fuel-and-gas mixture at adesignated ratio of fuel to gas, and the fuel-and-gas mixture conduitsare configured to direct the fuel-and-gas mixture out of the body andinto a combustion chamber of the engine cylinder.
 2. The mixingstructure of claim 1, wherein the body is a single, monolithic, seamlessstructure.
 3. The mixing structure of claim 1, wherein the gas channelsextend through the body such that the gas is drawn from the outside ofthe body into the central volume of the body.
 4. The mixing structure ofclaim 1, wherein the designated ratio of the fuel-and-gas mixture iscontrolled based on at least one of a number, shape, location, or sizeof one or more of the gas channels or the mixture conduits.
 5. Themixing structure of claim 1, wherein the gas channels have undulatingshapes in the body between the outward facing surface and the inwardfacing surface of the body.
 6. The mixing structure of claim 1, whereineach of the mixture conduits is configured to create one or more ofspin, swirl, or turbulence in the fuel-and-gas mixture flowingtherethrough.
 7. The mixing structure of claim 1, wherein the mixtureconduits extend radially outward from the axis and are configured thateach stream of the fuel-and-gas mixture is centered in the mixtureconduit in which the stream of the fuel-and-gas mixture flows.
 8. Themixing structure of claim 1, wherein the injector side of the bodydefines a step portion to avoid contact between the body and one or moreinlet or outlet valves of the engine cylinder during operation of theengine.
 9. The mixing structure of claim 1, wherein at least a portionof the body is surface treated or coated.
 10. A mixing structure,comprising: a body configured to be positioned between a fuel injectorand a cylinder of an engine along an axis of the body, the body definingan interior volume and having undulating fins that are spaced apart fromeach other around the axis of the body and around the interior volume,the undulating fins defining gas channels radially extending through thebody from outside of the body to the interior volume, the undulatingfins elongated in directions that are parallel to the axis of the body,the interior volume of the body configured to receive gas from outsidethe body through the gas channels and to receive one or more streams offuel from the fuel injector in the interior volume, and the bodydefining one or more mixture conduits configured to conduct plumes ofthe fuel and gas, while mixing, from the interior volume to one or moreexit ports and therethrough to the cylinder.
 11. The mixing structure ofclaim 10, wherein the undulating fins of the body are configured to coolthe gas prior to or during the mixture of the gas and the fuel in theinterior volume and the one or more mixture conduits.
 12. The mixingstructure of claim 10, wherein the body has an interface structure thatdefines at least one alignment hole or an alignment pin, and whereby themixture conduits each align with a nozzle of the fuel injector.
 13. Themixing structure of claim 12, wherein the interface structure is shrinkfit, press fit, welded, bolted to, threaded to, or formed as part of acylinder head of the engine cylinder.
 14. The mixing structure of claim10, wherein the mixture conduits define one or more apertures thatconnect to the gas channels, and the mixture conduits are configured todirect flows of the gas from the gas channels into the mixture conduitduring operation of the cylinder.
 15. The mixing structure of claim 10,wherein each of the mixture conduits includes one or more dimples,textured surfaces, grooves or protuberances to facilitate mixing of thefuel and gas plumes flowing through the mixture conduits.
 16. The mixingstructure of claim 10, wherein the mixture conduits are configured tomix the fuel and gas to a homogeneous state prior to combustion of theplumes in the cylinder.
 17. The mixing structure of claim 16, whereinthe mixture conduits are configured to direct the plumes into thecylinder such that, relative to combustion in the cylinder withoutmixing the fuel and the gas to the homogeneous state, a relativelyreduced amount or no amount of soot, nitrous oxides, or both soot andnitrous oxides are produced in the cylinder.
 18. The mixing structure ofclaim 10, wherein the body has a step portion to extend a path length ofthe one or more mixture conduits while avoiding contact of the body withone or more valves of the engine cylinder.
 19. A mixing structure,comprising: means for separately receiving fuel from a fuel injector andreceiving gas, the means for separately receiving the fuel and receivingthe gas including undulating fins that are spaced apart from each otheraround an axis, the undulating fins defining radially extending gaschannels that are elongated in directions that are parallel to the axis;means for mixing the fuel and the gas into a fuel-and-gas mixture at adesignated ratio; and means for directing the fuel-and-gas mixture intoa combustion chamber of an engine cylinder.
 20. The mixing structure ofclaim 19, wherein the means for separately receiving the fuel andreceiving the gas cools the gas prior to or while the gas is mixing withthe fuel.
 21. The mixing structure of claim 19, wherein the means formixing the fuel and the gas into the fuel-and-gas mixture comprises: amixture conduit having inner walls and means for inducing turbulenceinto fuel and gas streams to increase homogeneity of the fuel-and-gasmixture, and means for centering and spacing a flow of the fuel-and-gasmixture from the inner walls of the mixture conduit.
 22. The mixingstructure of claim 19, wherein the means for directing the fuel-and-gasmixture into the combustion chamber: directs the fuel-and-gas mixture topenetrate into the combustion chamber of the engine cylinder prior tocombustion, or delays the combustion of the fuel-and-gas mixture, orboth directs the fuel-and-gas mixture into the combustion chamber of theengine cylinder prior to combustion and delays the combustion of thefuel-and-gas mixture.